* Basque (Euskera) is a language isolate, meaning it is not related to any other known language. It is believed to be a remnant of a prehistoric language family that existed in Europe before the arrival of Indo-European languages.
* Galician belongs to the Romance language family, specifically the Western Romance group. It is a daughter language of Latin, just like Spanish, Portuguese, Catalan, French, and others. Galician evolved from the Vulgar Latin spoken in the northwestern Iberian peninsula during the Roman Empire.
Therefore, while both Basque and Galician are spoken in Spain, they have entirely different linguistic roots and histories.